Journal Article 2D tellurium 2D van der Waals heterostructures Review defect engineering electronics elemental 2D materials ferroelectric polarization floating gate in-sensor reservoir computing liquid‐gated transistor liquid‐phase exfoliation multimodal reservoir computing neuromorphic computing optical communication band optoelectronic memory device optoelectronic memory devices optoelectronics reconfigurable memory device synthesis methods tellurene tellurium tellurium nanoflake van der Waals heterostructure van der Waals heterostructures van der Waals materials xenes